Field of the Invention
The present invention relates to non-invasive sonication of multiple samples and to the continuous sonication of effluent streams in flow-through arrangements using optimized coupling of vibrating elements and the sample containers.
Background and Prior Art
The present invention describes a sonication device for the breakage of the constituents present in a liquid sample. The invention addresses multiple samples and continuous sonication of an input fluid stream in flow-through arrangements, particularly useful for economical breakdown of organisms in large volumes.
By sonication, it is meant applying mechanical vibration energy at particular frequency to a sample. The sample is generally a liquid containing suspended items of interest. The vibration frequencies are generally in the ultrasonic range. Ultrasonic energy is transmitted in a medium through wave propagation which causes pressure changes within the medium. Suspended items which are unable to withstand the pressure changes are disrupted.
“Sonicators” are generally constructed from an electrical power supply, power control circuitry, vibrating elements, and implements coupled to the vibrating element, which delivers energy to intended samples. Examples are described in my U.S. Pat. No. 6,071,480. The electrical power supply and electronics provides controllable oscillating energy in the ultrasonic frequency range. The vibrating element is a transducer or an actuator, typically a substance that converts electrical energy into mechanical vibrations. The vibrational energy is transferred to vibratable elements such as a probe (probe sonicators), liquid container (bath sonicators), or a horn. A converter is sometimes inserted between the vibratable element and the transducer, for the purpose of modifying the energy density. Piezoelectric transducers, such as piezoelectric crystals or ceramics, are generally used as vibrating elements and are extensively studied in the art to convert electrical energy into mechanical energy. Multiple transducers can be stacked, and several such configurations are also known in the art. The vibratable element is coupled to the transducer and acts as a conveyer to deliver the vibrational energy, optionally through other end-use implements, to the intended sample.
By coupling, it is meant the interface between two distinct components. In ultrasonic devices, coupling is applied to reduce the energy loss as the vibrational energy moves across distinct component interfaces. Coupling typically attempts to match, or minimize the difference between, the acoustic impedance of disparate interacting components.
Sonication energy is utilized in a wide variety of industrial and biological applications. For biological samples, applications include lysis, or breakage, of biological microorganisms, including bacteria, viruses, spores, plant cells, etc.
In applying to biological material, sonication devices (sonicators) most commonly used are bath sonicators, in which an ultrasonic device energizes water in a bath. Tubes containing samples to be sonicated are placed in the bath. The ultra-sonic waves produced by the sonication device transfer into the bath liquid and further to the sample tubes to break the organisms therein. U.S. Pat. No. 4,874,137, and U.S. Pat. No. 6,939,696 disclose arrangements of bath sonicators. Bath sonicator arrangements generally suffer from inefficient utilization of provided energy. U.S. Pat. No. 4,697,751 describes an ultrasonic disintegrating apparatus with a tank containing a liquid and with an ultrasonic wave generator means coupled to a bottom wall of said tank.
The invention also describes arrangements for continuous flow-through useful for large sample volumes. These arrangements allow the use of relatively low power sonication energy to affect large sample volumes, and overcome some of the limitations present in prior art.
U.S. Pat. No. 7,785,869 and similarly U.S. Pat. No. 7,541,166, describe sonication to selectively lyse different cell types using different sonication energy and using microfluidic circuitry for moving fluids.
U.S. Pat. No. 6,016,023 describes a tubular ultrasonic transducer with a gas cooling features to cool the transducer.
U.S. Pat. No. 5,074,474 describes an arrangement which includes the direct immersion of the tip, or horn, of the sonication device into the sample. While this arrangement provides an efficient utilization of energy, it suffers from cross contamination issues and more complicated workflow.
U.S. Pat. No. 4,983,523 describes an arrangement where ultrasonic energy is directly applied to (the outside of) a vessel containing a sample.
U.S. Pat. No. 7,004,282 describes an ultrasonic horn to provide an ultrasonic device that could treat a full microtiter tray, with the ultrasonic horn having a plurality of fingers disposed in a rectangular array for that purpose.
U.S. Pat. No. 6,686,195 describes method and apparatus for ultrasonic lysis of biological cells, where a “sonotrode” provides ultrasound of variable power to a sample receptacle where the bottom of the sample receptacle is in direct contact with the sonotrode. The sample receptacles were kept in place by variable weight forces on top of each tube to minimize lysis variability.
My U.S. Pat. No. 6,071,480 describes a sonicator having an electrical wave generator, a vibrating element electrically connected to the electrical wave generator and a vibratable member transversely secured to the vibrating element. The sonicator can be employed to sonicate a test sample by generating a standing sonic wave across a vibratable member. U.S. Pat. No. 6,071,480 provides the sonication of discrete test samples, but does not disclose arrangements or methods for continuous sonication applicable to large volumes. Although methods of modifying the holes in the plates using, e.g. threads, are mentioned in U.S. Pat. No. 6,071,480, no description of the tube attachment features to optimize the vibrational coupling of the tubes to the plate is detailed. Additionally, the attachment of the sample tube to the plate is operator-dependent in that the torque applied is not calibrated and as such is subject to the operator judgment and physical strength.